In many countries, compositions such as oral care compositions are required to comply with certain standards regarding the level of microbes present therein and/or the resistance of the compositions towards microbial attack. In order to ensure that compositions comply with these standards, several initiatives and tools may be implemented throughout the manufacturing process. Resistance of the composition to microbial attack (sometimes termed “micro-robustness”) is one of the key elements used to ensure compliance. However, as technology advances, new methods of manufacturing such compositions are introduced. One such technology is the post addition system of manufacturing, in which a partially-complete (i.e. unfinished) composition is prepared and is stored for a certain period of time, after which the remaining ingredients are added in order to form the finished product. The unfinished composition therefore does not contain all the ingredients which are to be included in the finished product, and thus may be more susceptible to microbial attack. Therefore, there is a risk that the unfinished product may become contaminated with microbes, resulting in the finished product having microbial levels which are above the maximum threshold specified by the standards. It would be desirable to increase the resistance to microbial attack of both the finished and unfinished product in such a system of manufacturing.